package 剑指Offer1;

public class _23青蛙跳台阶问题 {
    public int numWays(int n) {
        if(n<=1) return 1;
        int[] dp = new int[n+1];
        dp[0] = 0;dp[1] = 1;
        for(int i=2;i<=n;i++){
            dp[i] = dp[i-1] + dp[i-2]%1000000007;
        }
        return dp[n];
    }
}
